The proposed studies will characterize temporally the activation and localization of various complement components in ischemic and infarcted myocardium. An experimental model in the baboon has been developed for the studies. The role of complement activation and/or localization in the development of "border" or marginal zones following coronary artery ligation will be addressed and it will be determined whether injury in these jeopardized areas is reversible with suitable intervention. Studies will be conducted to characterize complement (Clq) binding sites on subcellular membranes and possibly on the plasma membranes of tissue culture cells (vascular smooth muscle) exposed to low oxygen tension and reduced levels of substrates. It is hoped that these studies will elucidate the role and mechanisms of complement-mediated myocardial tissue injury induced by ischemia and provide a means whereby appropriate interventions can be established to reduce myocardial infarct size.